Anyone shopping for a boating GPS app in the United States runs into the same shortlist: Helm Boating, Savvy Navvy, Navionics Boating from Garmin, iNavX and i-Boating. They all put a nautical chart on your phone. What separates them is what the app does with that chart once it is on screen — which data it reads, how it treats depth, and how much of it still works when the signal drops.
This page sets out exactly what Helm does, source by source, so you can hold it against whatever else you are considering. Helm Boating is published on the App Store as Helm Boating: GPS, Chart & Map, built by Loop Mobile FZCO in Dubai, United Arab Emirates, and it is free to download.
The column on the right is deliberately left empty: every app handles these differently and the only honest answer for a third-party product is to check its own listing. The middle column is Helm, and every line in it is something the app does today.
| What to compare | Helm Boating | Other apps |
|---|---|---|
| Chart source | Built from NOAA electronic navigational chart (ENC) data, reprocessed by Helm; US Army Corps of Engineers Inland ENC on the rivers | Varies by app |
| Depth sources | The chart (NOAA ENC, or USACE Inland ENC on rivers), plus the NOAA CO-OPS predicted tide where a station is close enough | Varies by app |
| What the depth figure is | The card says whether it is a charted sounding, a depth band or water the chart has no soundings for | Varies by app |
| Your boat's draft | Entered once; water you cannot cross is shaded where the chart carries depth, and routes plan around it on the coast and Lakes Michigan, Erie and Ontario | Varies by app |
| Inland lakes | Shorelines and names from the USGS National Hydrography Dataset in 48 state packs; Minnesota adds state contour lines | Varies by app |
| Offline coverage | 161 downloadable chart packs; charts, depth where the chart carries it, routing in the coastal and Great Lakes packs that carry it, tides and the anchor alarm run from the device | Varies by app |
| Tides and currents | NOAA CO-OPS predictions on the MLLW datum; current arrows rotate as you scrub through the day | Varies by app |
| Weather | Animated wind, wave and current overlays, multi-day strip with three-hour columns | Varies by app |
| Underway display | Depth, speed over ground and course over ground on one strip, anchor alarm, AIS, satellite and night styles | Varies by app |
| Logbook | Trips run on a route are recorded and reopen on the chart | Varies by app |
| iPad | Native iPad layout | Varies by app |
| CarPlay | Chart view on the vehicle's built-in display | Varies by app |
"Best charts" is really a question about data. Helm is built from NOAA electronic navigational charts in the S-57 vector format published by NOAA's Office of Coast Survey, reprocessed into Helm's own chart packs. Soundings, contours, buoys, beacons, obstructions and channel limits in the app come from that NOAA data. On the inland rivers the same kind of chart comes from the US Army Corps of Engineers.
Because an ENC is structured data rather than a picture, Helm can do arithmetic with it. A shoal at the mouth of an inlet is an object with a depth value, so the app can compare it to your boat's draft and answer the question directly.
A charted sounding describes the bottom at the moment it was surveyed, at chart datum. Where a NOAA tide station is within 25 nautical miles, the depth card adds that station's predicted tide from NOAA CO-OPS, so you read depth at the hour you are looking rather than depth at chart datum. Elsewhere the card shows the depth at chart datum.
The card also says what kind of figure you are reading: a charted sounding, a depth band from the chart, or water the chart has no soundings for.
Savvy Navvy is a well-known passage-planning app among coastal boaters. If you are weighing it against Helm, these are the points where Helm's approach is specific enough to check line by line:
Both apps are on the App Store, and each listing sets out its own chart sources and coverage. That is the comparison worth reading before you pick.
Navionics Boating is Garmin's marine chart app and a familiar name on US boats. Offline behavior is the right axis to compare on, because it is the one that matters at the exact moment you cannot check anything: ten miles out, or on a lake with no bars.
In Helm, coverage is packaged into 161 downloadable chart packs. You take the regions you run and leave the rest. Once a pack is on the device, the following run with no cell service at all:
Sign in to the same account on each device and your routes, saved spots, recorded trips and chart drawings sync when you are back in range, so a spot saved on the phone at the ramp is on the iPad at the helm.
iNavX is a long-established chartplotter app with a following among offshore sailors. Helm is built around one question — what is under the hull, and can this boat cross it — and answers it with charted depth read against your draft, the predicted tide added where a station is close, and draft-aware routing, on charts built from NOAA data, offline, on iPhone, iPad and CarPlay.
This is the case Helm was built for. Your draft is part of the chart, the water you cannot cross is shaded, and routes are planned around it instead of straight through it.
Helm's 48 state lake packs draw lake shorelines and names from the USGS National Hydrography Dataset, and Minnesota adds Minnesota DNR contour lines on its lakes. The Great Lakes are on NOAA charts and carry charted depth. Every lake pack works with no signal once it is downloaded.
Save spots, read the depth contours around them, and come back to the same place later from your recorded trips, with water temperature in the forecast strip where data exists.
Helm has a native iPad layout and a CarPlay interface, so the same charts and the same saved routes follow you from the car to the console.
Judge it on data, not on the map style. Ask which charts the app reads, whether it adds anything to them, whether it knows your boat's draft, and what still works offline. Helm Boating is built from NOAA electronic navigational chart data, with US Army Corps of Engineers charts on the rivers, adds the NOAA CO-OPS predicted tide to the charted depth where a station is close enough, tells you whether a figure is a charted sounding or a depth band, plans routes around water too shallow for your draft in its coastal and Great Lakes packs, and runs from 161 downloadable chart packs with no cell service.
Charts come down to the data underneath them. Helm is built from NOAA ENC vector data, reprocessed by Helm, with US Army Corps of Engineers inland charts on the rivers, and adds the NOAA predicted tide to the charted depth where a station is close enough. Savvy Navvy, Navionics Boating, iNavX and i-Boating each describe their own chart sources on their listings, and that is the comparison worth making.
Both are marine navigation apps with passage planning. Helm's specifics: charted depth read against your draft with the predicted tide added where a station is close, draft-aware routing that shows the shallowest point on a leg, US Army Corps of Engineers charts on the inland rivers, 161 offline chart packs, AIS, anchor alarm, logbook, native iPad and CarPlay.
Compare them on what keeps running when the signal is gone. With a Helm chart pack on the device, the NOAA charts, depth against your draft where the chart carries it, draft-aware routing in the coastal and Great Lakes packs that carry it, the measure tool, tides and currents, the anchor alarm and trip recording all keep working offline. Coverage is split into 161 packs so you download only the water you run.
Yes. Coastal water, the intracoastal, rivers and inland lakes. The rivers come from US Army Corps of Engineers charts and carry depth. The state lake packs draw lakes by name and shoreline from the USGS National Hydrography Dataset, and Minnesota also has state depth contours.
Yes. The iPad layout is native rather than a stretched phone screen, and with a subscription the chart view appears on a CarPlay vehicle's built-in display.
Loop Mobile FZCO, a software company registered in Dubai, United Arab Emirates. The app is listed on the US App Store as Helm Boating: GPS, Chart & Map and is free to download.
Helm is free to download, and the charts, chart pack downloads, draft-aware route planning, search and the measure tool work without a subscription. The subscription is $99.99 per year — about $8.33 a month — and starts with a free trial. It adds the depth reading under your keel when you tap the chart, the Tides, Weather, Waves and Logbook tools, satellite and night chart styles, the wind, wave and current overlays, AIS, drawing on the chart, the anchor alarm and CarPlay. You pay nothing during the trial; when it ends, Apple bills the subscription unless you cancel before then.
There is no chart cartridge to buy, no plotter to own and no separate chart library to subscribe to. The NOAA chart data Helm is built from is public. Billing is handled by Apple, so the subscription is cancelled from your own Apple ID settings at any time.
If you are still choosing, we also wrote a straight comparison of the best marine navigation apps for US waters in 2026, with every price read off the App Store.
Helm Boating